Re: slight tweaks to documentation about runtime pruning
Amit Langote <langote_amit_f8@lab.ntt.co.jp>
From: Amit Langote <Langote_Amit_f8@lab.ntt.co.jp>
To: Amit Langote <amitlangote09@gmail.com>,
David Rowley <david.rowley@2ndquadrant.com>
Cc: PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2018-12-14T02:52:03Z
Lists: pgsql-hackers
Attachments
- runtime-pruning-doc-tweak-v2.patch (text/plain) patch v2
On 2018/12/10 0:57, Amit Langote wrote: > On Sun, Dec 9, 2018 at 8:13 PM David Rowley > <david.rowley@2ndquadrant.com> wrote: >> listp1 was scanned twice (loops=2), listp2 was scanned just once. >> >> Now it is true that if the subplan was executed 0 times that it will >> appear as "(never executed)", but do we really need to explain in this >> area that "(never executed)" means loops=0? > > Ah, I see what you mean. So, "(never executed)" is not the only sign > of of run-time pruning occurring. The value of loops can be different > for different subplans / partitions, and it being lower for a given > subplan means that the subplan has been pruned more number of times. I updated the patch. Regarding whether we should mention "(never executed)", it wouldn't hurt to mention it imho, exactly because it's shown in the place of showing loops=0. How about the attached? Thanks, Amit
Commits
-
Clarify runtime pruning in EXPLAIN
- 1e6240a3fe91 12.0 landed
- f760a8b5cc1f 11.2 landed